ISO 6721-4:2019

INTERNATIONAL ISO
STANDARD 6721-4
Third edition
2019-05
Plastics — Determination of dynamic
mechanical properties —
Part 4:
Tensile vibration — Non-resonance
method
Plastiques — Détermination des propriétés mécaniques
dynamiques —
Partie 4: Vibration en traction — Méthode hors résonance
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Test device . 2
5.1 Loading assembly . 2
5.1.1 General. 2
5.1.2 Clamps . 2
5.1.3 Transducers. 2
5.2 Electronic data-processing equipment . 2
5.3 Temperature measurement and control . 2
5.4 Devices for measuring test specimen dimensions . 3
6 Test specimens. 3
6.1 General . 3
6.2 Shape and dimensions . 3
6.3 Preparation . 4
7 Number of specimens . 4
8 Conditioning . 4
9 Procedure. 4
9.1 Test atmosphere . 4
9.2 Measurement of specimen cross-section . 4
9.3 Clamping the specimen. 4
9.4 Varying the temperature . 4
9.5 Performing the test. 5
10 Expression of results . 5
10.1 Symbols . 5
10.2 Calculation of the tensile storage modulus E′ . 6
10.2.1 General. 6
10.2.2 Avoidance of specimen resonance . 6
10.2.3 Correction for transducer resonance . 7
10.2.4 Correction for apparatus compliance . 7
10.2.5 Application of a length correction . 7
10.3 Calculation of the tensile loss factor tan δ . 8
E
10.4 Calculation of the tensile loss modulus . 8
10.5 Presentation of data as a function of temperature . 8
11 Precision . 8
12 Test report . 8
Bibliography . 9
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This third edition cancels and replaces the second edition (ISO 6721-4:2008), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the document has been revised editorially;
— normative references have been changed to undated.
A list of all parts in the ISO 6721 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 6721-4:2019(E)
Plastics — Determination of dynamic mechanical
properties —
Part 4:
Tensile vibration — Non-resonance method
1 Scope
This document describes a forced, non-resonance method for determining the components of the tensile
complex modulus E* of polymers at frequencies typically in the range 0,01 Hz to 100 Hz.
NOTE Higher frequency measurements can be made, but significant errors in the dynamic properties
measured are likely to result (see 10.2.2 and 10.2.3).
The method is suitable for measuring dynamic storage moduli in the range 0,01 GPa to 5 GPa. Although
materials with moduli outside this range can be studied, alternative modes of deformation are intended
to be used for higher accuracy [i.e. a shear mode for G′ < 0,01 GPa (see ISO 6721-6) and a flexural mode
for E′ > 5 GPa (see ISO 6721-3 or ISO 6721-5)].
This method is particularly suited to the measurement of loss factors and can therefore be conveniently
used to study the variation of dynamic properties with temperature and frequency through most of the
glass-rubber relaxation region (see ISO 6721-1). The availability of data determined over wide ranges
of both frequency and temperature enables master plots to be derived, using frequency-temperature
shift procedures, which display dynamic properties over an extended frequency range at different
temperatures.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6721-1, Plastics — Determination of dynamic mechanical properties — Part 1: General principles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6721-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Principle
The specimen is subjected to a sinusoidal tensile force or deformation at a frequency significantly
below the fundamental resonance frequency for the clamped/free longitudinal mode (see 10.2.2). The
amplitudes of the force and displacement cycles applied to the specimen and the phase angle between
these cycles are measured. The storage and loss factor are calculated using formulae given in Clause 10.
5 Test device
5.1 Loading assembly
5.1.1 General
The requirements on the apparatus are that it shall permit measurements of the amplitudes of, and
the phase angle between, the force and displacement cycles for a specimen subjected to a sinusoidal
tensile force or deformation. Various designs of apparatus are possible: a suitable version is shown
schematically in Figure 1. A sinusoidal force is generated by the vibrator V and applied to one end of the
specimen S by means of the clamp C . The amplitude and frequency of the vibrator table displacement
are variable and monitored by the transducer D. The member between V a
...